1. Field of the Invention
This invention relates to test equipment for computing systems and more particularly relates to an interface adapter unit which permits a remotely located data processing unit to be connected to an on-site computing system for purposes of maintenance or for remote control.
2. Description of the Prior Art
Most medium and large scale central processing units are equipped with maintenance panels to enable service personnel to make electrical and/or visual test of check points in the central processing system. As a general rule, the larger the central processing unit larger and more sophisticated the maintenance panels.
Some large scale central processing units are provided with maintenance controllers. Such maintenance controllers do not provide the same measure of control as the central control panel. Some maintenance controllers are provided with a plurality of selector switches which permit service personnel to manually set up conditions which simulate a software step input or a control step. In order that the information set in the manual switches of a maintenance controller be converted into instructions and data for use by the central processing system, the central processing unit must be in operable condition.
The Model 1929 Maintenance Controller, designed for use with the Model 1110 Central Processing Unit, made by Sperry Rand Corporation comprises an on-site processor which permits the controller to run a test program and to compare the test program results with correct test results accompanying the test program. The test program, even though limited to four functions, similar to the manually set switches in the maintenance panels, could run a test program separate and apart from the operation of the on-site central processing unit.
Heretofore, central processing systems have included a plurality of central processing units. The mode of operation of such systems is capable of connecting one central processing unit to another for the transfer of information therebetween.
Heretofore, central processing units in two different locations, remote from each other have been effectively connected to each other by employing interface adapters connected to telephone modems which are in turn connected by telephone lines. Such connections permit the transfer of information between computing systems.
During the manufacture of central processing units and/or peripheral equipment, simulators or processors are employed to electrically test the apparatus after it is assembled. After the processing units and peripheral equipment is shipped from the factory and assembled into a central processing system such simulated tests cannot be made.
Heretofore, maintenance panels have been limited to manually settable switches for simulating a limited amount of test information. Such maintenance panels could not operate the peripheral equipment without an operable central processing unit.
Heretofore, maintenance controllers have been limited to performing only a few selected functions of the many performable by a central processing unit. Such prior art maintenance controllers have not been provided with a direct interface connected to the central processing unit console or to the auxilliary consoles of the peripheral equipment, so that all equipment could be operated in a computer operated mode. When the on-site central processing unit malfunctions and/or the peripheral equipment malfunctions in a manner that requires high speed computer analysis, the prior art maintenance controllers and maintenance panels do not provide adequate means to diagnose and correct the problem.
It has been suggested that large central processing systems could be provided with a standby central processing unit which could be used for back-up and/or test purposes. Not only is this a very expensive luxury, but it presumes that each such installation is provided with a large library of special test programs.
Now that computers are being manufactured with solid state logic components and solid state memory components, there is an attempt to perform electronic switching functions faster and faster. The fastest components being employed today become metastable or unstable when switched too fast. It is possible for fast switching components to operate correctly for one program step or operation and to perform incorrectly when the identical step is presented in a different series of steps. Further, the step or malfunction may occur in the middle or near the end of a program comprising thousands of steps. A malfunction of this type is usually not detectable by making manual or slow step-by-step analysis. The only practical way to detect high speed errors is to operate the piece of equipment giving the problem at high speed and under the same conditions under which the error occurred. Heretofore, such diagnostic equipment was not available in a single unit of any type except at the factory where simulators and processors are employed to check out newly manufactured equipment.
There is an unfulfilled need for a reliable economical piece of equipment which can perform the functions of factory simulators and processors and could be transported to a central processing system site to perform diagnostic tests on the central processing unit as well as the peripheral equipment.